SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd94f1dce939887145a8bfcc013306d35ebf774b25badc95acef3638c8fda427' 
  AND token = 'xPJJjWPi21d12QnLcNpXCy3xgCDKqmX+hftYMqjY8OM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}